Vertical axis wind turbine bearing axial load sharing

Abstract

A vertical axis wind turbine (VAWT) assembly effects sharing of the axial load on its bearings to increase equipment life and/or effective operation. The assembly includes: a support; a VAWT (e.g. Savonius) having a substantially vertical shaft; at least lower and upper substantially vertically spaced bearings mounting the shaft for rotation about a substantially vertical axis, the bearings operatively mounted by the support; and a load-sharing assembly connected to the upper bearing which allows the bearings to share at least 10% (such as 50-50) of the axial load. The load sharing assembly may include a spring surrounding an upper portion of the shaft, and operatively engaging the upper bearing. The shaft may include an upper shall extension, and the load sharing assembly a spring end cap operatively connected to the upper shaft extension and holding the spring against the upper bearing.

1. A vertical axis wind turbine assembly comprising:
 a support; a vertical axis wind turbine having a substantially vertical shaft; at least first, lower, and second, upper, substantially vertically spaced bearings mounting the shaft for rotation about a substantially vertical axis, the bearings operatively mounted by the support; and a load-sharing assembly operatively connected to the second bearing which allows the bearings to share at least about 10% of the axial load on the bearings. 
 
     
     
       2. An assembly as recited in  claim 1  wherein the bearings are radial ball bearings. 
     
     
       3. An assembly as recited in  claim 1  wherein the load sharing assembly comprises at least one coil or conical spring surrounding an upper portion of the shaft, and operatively engaging the second bearing. 
     
     
       4. An assembly as recited in  claim 3  wherein the shaft includes an upper shaft extension, and wherein the load sharing assembly further comprises a spring end cap operatively connected to the upper shaft extension and holding the spring against the second bearing. 
     
     
       5. An assembly as recited in  claim 1  wherein the vertical axis wind turbine comprises a Savonius wind turbine, operatively connected to a utilization device. 
     
     
       6. An assembly as recited in  claim 1  wherein the support comprises a three legged frame having support arms extending radially inwardly from the frame legs and supporting the first and second bearings. 
     
     
       7. An assembly as recited in  claim 1  wherein the load sharing assembly comprises at least one spring operatively connected to the shaft and operatively engaging the second bearing. 
     
     
       8. An assembly as recited in  claim 7  wherein the spring consists essentially of a single coil or conical spring. 
     
     
       9. An assembly as recited in  claim 8  wherein the spring constant of the spring is selected with respect to the total axial loading of the bearings so that the bearing load sharing will be roughly about 50-50. 
     
     
       10. An assembly as recited in  claim 1  wherein the bearings consist essentially of only the first and second bearings. 
     
     
       11. An assembly as recited in  claim 10  wherein the load sharing assembly comprises at least one spring operatively connected to the shaft and operatively engaging the second bearing. 
     
     
       12. An assembly as recited in  claim 11  wherein said load sharing assembly comprises at least one spring operatively acting on the upper bearing, the spring constant or constants of which is or are selected so that the upper and lower bearings each share about 40%-60% of the total axial load on the bearings. 
     
     
       13. An assembly as recited in  claim 11  wherein the vertical axis wind turbine comprises a Savonius wind turbine, operatively connected to a utilization device. 
     
     
       14. A method of operating a vertical axis wind turbine having substantially vertically spaced at least upper and lower bearings by (a) distributing the axial loading between the bearings of the wind turbine so that each of the upper and lower bearings support at least about 10% of the total axial load. 
     
     
       15. A method as recited in  claim 14  wherein the vertical axis wind turbine comprises a Savonius, and further comprising (b) replacing both the upper and lower bearings of the Savonius at the same time after extended operation thereof. 
     
     
       16. A method as recited in  claim 14  wherein (a) is practiced so that the upper and lower bearings each support between about 30%-70% of the total axial load, and wherein (a) is practiced by selecting the spring constant or constants of at least one spring operatively acting on the upper bearing with respect to the total axial load including the weight of the wind turbine. 
     
     
       17. A method as recited in  claim 16  further comprising (c) adjusting the spring constant of, or replacing, the spring without an extended hiatus of operation of the VAWT so as to change the relative load sharing of the bearings depending upon which one is wearing more quickly during operation. 
     
     
       18. An assembly comprising: a support; an operable device having a substantially vertical shaft; at least first, lower, and second, upper, substantially vertically spaced bearings mounting the shaft for rotation or reciprocation, the bearings operatively mounted by the support; and a load-sharing assembly operatively connected to the second bearing which allows the bearings to share at least about 10% of the axial load on the bearings. 
     
     
       19. An assembly as recited in  claim 18  wherein said load sharing assembly comprises at least one spring operatively acting on the upper bearing, the spring constant or constants of which is or are selected so that the upper and lower bearings each share about 40%-60% of the total axial load on the bearings. 
     
     
       20. An assembly as recited in  claim 19  wherein said at least one spring consists essentially of a single coil or conical spring.